Liquid compositions containing urease inhibitors and aryl alkyl alcohols and methods of making and use thereof

ABSTRACT

The present invention provides improved solvent systems for the preparation of liquid formulations of urease inhibitors, specifically NBPT, comprising aryl alkyl alcohols. The solvent systems provided good solubility of the urease inhibitor as well as at least one of improved stability, lower flammability, lower toxicity, improved cold temperature storage, improved handling, improved adsorption onto and/or solubility with solid media such as urea. Methods of making and using the compositions are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) from U.S.Provisional Application 61/683,367, filed Aug. 15, 2012, which isincorporated by reference in its entirety herewith.

BACKGROUND OF THE INVENTION

Granular fertilizers have been used for some time to provide nitrogen tothe soil. The most widely used and agriculturally important nitrogenfertilizer is urea. Most of the urea currently produced is used as afertilizer in its granular (or prilled) form. However, after itsapplication to soil, its hydrolysis to yield ammonia and carbon dioxideoccurs. This process is catalyzed by the enzyme urease, which isproduced by some bacteria and fungi. The gaseous products formed by thehydrolysis reaction (ammonia and carbon dioxide) volatilize to theatmosphere and thus, substantial losses from the total amount of thenitrogen applied to the field occur. The hydrolysis process can beconsiderably decelerated by urease inhibitors that are applied togetherwith urea. Urease inhibitors can also be used in combination withnitrification inhibitors. Nitrification inhibitors are compounds whichinhibit the conversion of ammonium to nitrate and reduce nitrogen lossesin the soil. Examples of nitrification inhibitors include, dicyandiamide(DCD).

Examples of urease inhibitors are the thiophosphoric triamide compoundsdisclosed in the U.S. Pat. No. 4,530,714, including N-(n-butyl)thiophosphoric triamide (NBPT), the most developed representative ofthis class of compounds. When incorporated into a urea-containingfertilizer, NBPT reduces the rate at which urea is hydrolyzed in thesoil to ammonia. The benefits realized as a result of the delayed ureahydrolysis include the following: (1) nutrient nitrogen is available tothe plant over a longer period of time; (2) excessive build-up ofammonia in the soil following the application of the urea-containingfertilizer is avoided; (3) the potential for nitrogen loss throughammonia volatilization is reduced; (4) the potential for damage by highlevels of ammonia to seedlings and young plants is reduced; (5) plantuptake of nitrogen is increased; and (6) an increase in crop yields isattained. The use of NBPT is commercially, available for the use inagriculture and marketed in such protects as the AGROTAIN® nitrogenstabilizer product line.

Industrial grade N-(n-butyl) thiophosphoric triamide (NBPT) is a solid,waxy compound, and decomposes by the action of water, acid and/orelevated temperature. Accordingly, its combination with other solidmaterials is very difficult. The use of a liquid formulation of the NBPTis highly desirable because it greatly facilitates the introduction ofthe NBPT onto other solid materials, such as the PERGOPAK® M used inAGROTAIN DRY® and formulation with granular urea. The impregnation ofNBPT onto a UFP, such as PERGOPAK® M or other solids, such as granularurea requires the NBPT to be introduced into some liquid carrier priorto being mixed with the solid. The dissolution of NBPT with or withoutUFP into liquid urea-containing fertilizers, such as, urea-ammoniumnitrate solutions (UAN), is also facilitated by having the NBPT in aneasily assimilated liquid formulation.

However NBPT is very difficult to solubilize in a concentrated solution.Accordingly, a variety of solvent mixtures have been tried, includingthose disclosed in U.S. Pat. Nos. 5,352,265 and 5,364,438 (usingN-methyl pyrrolidine, NMP); U.S. Pat. No. 5,698,003 (using propyleneglycol or dipropylene glycol alone or in combination with NMP orpoly(oxy-1,2-ethanediyl)-alpha (nonylpheoyl)omega-hydroxy); and U.S.Pat. No. 8,048,189 (using ethanolamine, diethanolamine, triethanolamine,monoisopropanolamine, or diisopropanolamine buffered with acetic acid);PCT Patent Publication WO 2008/000196 (using dipropyleneglycolmonomethylether, diethyleneglycol monomethylether, triethyleneglycolmonomethylether or diethyleneglycol monobutylether in combination withpolyvinylpyrrolidone (PVP) or NMP); CA. Patent publication 2701995(using water); U.S. Patent Publication Nos. 2010/0168256 (using water);2010/0206031 and 2011/0259068 (using glycerol aqueous sorbitolethanolamine, diethanolamine or triethanolamine); 2011/0113842 (usinggarlic essential oil in combination with sodium hydroxide ortriethanolamine); and 2011/0333474 (using (S)-ethyl lactate or propylenecarbonate in combination with tetrahydrofurfuryl alcohol, PVP, NMP,glycerol formal, propylene glycol and/or water).

However, both area and solvents containing hydroxyl groups arehydroscopic which causes problems with NBPT formulations, especiallywith urea. Water can facilitate the decomposition of N-(n-butyl)thiophosphoric triamide (NBPT) into non-effective substances. Inaddition, water cause's stickiness, dumping and caking of urea-based,granular fertilizers which reduces the flowability of urea-basedgranular fertilizers, and the like and complicates their handling. Theseproblems are exacerbated during storage of these materials.

Accordingly, at least 10 wt. % of NMP or 0.1% of PVP is often usedeither as a co-solvent or as a crystallization inhibitor. However,amides like NMP and PVP can be health deleterious. N-methylpyrrolidoneis often classified among teratogenic compounds and accordinglymanufacturers must consider alternative solvents, especially whereworker exposure is difficult to control (see e.g. Chemical & EngineeringNews: 32 (Jul. 21, 2008)). In addition, PVP has been documented to causeallergic reactions, particularly when applied to the skin or where ithas come into contact with mucous membranes (see e.g. K. Yoshida et al.(2008) International Archives of Allergy and Immunology 146 (2); 169-73(2008); A. Adachi et al. Contact Dermatitis 48 (3): 133-6 (2003); A. C.Rönnau et al. The British Journal of Dermatology 143 (5): 1055-8(2000)).

The above, mentioned disadvantages are overcome by the compositions ofthe present invention which provide compositions with reduced, healthrisk and/or toxicity, lower volatility and flammability, increasedstability of NBPT and other components in the composition, the abilityto be used/stored at lower application temperatures, and/or usingcommercially available, low cost materials as compared to previous theprevious art.

The present invention relates to a composition comprising a ureaseinhibitor and an aryl alkyl alcohol solvent. The present invention alsorelates to methods of making the compositions and their use inagricultural applications.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the below terms have the following meanings unlessspecified otherwise;

1. Abbreviations and Definitions

It is noted here that as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referenceunless the context clearly dictates otherwise.

All percentages, pans and ratios are based upon the total weight of thecompositions of the present invention, unless, otherwise specified. Allsuch weights as they pertain to listed ingredients are based on theactive level and therefore do not include solvents or by-products thatmay be included in commercially available materials, unless otherwisespecified. The term “weight percent” may be denoted as “wt %” herein.All molecular weights as used herein are weight average molecularweights expressed, as grams/mole, unless otherwise specified.

As noted above, the present invention provides an improved formulationfor urease inhibitors, for example N-(alkyl) thiophosphoric triamideurease inhibitors as described in U.S. Pat. No. 4,530,714, dial areuseful in agricultural applications. The present invention also includesthiophosphoric triamides and phosphoric triamides of the general formula(I)X═P(NH₂)₂NR¹R²  (I)where X=oxygen or sulfur, and R¹ and R² are independently selected fromhydrogen. C₁-C₁₂ alkyl, C₃-C₁₂ cycloalkyl C₆-C₁₄ aryl, C₂-C₁₂ alkenyl,C₂-C₁₂ alkynyl, C₅-C₁₄ heteroaryl, C₁-C₁₄ heteroalkyl, C₂-C₁₄heteroalkenyl, C₂-C₁₄ heteroalkynyl, or C₃-C₁₂ cycloheteroalkyl groups.

It should be understood that the term N-(alkyl) thiophosphoric triamideas used throughout this application refers not only to the N-(alkyl)thiophosphoric triamide in its pure form, but also to commercial gradesof the material which can contain up to 50 percent (or less), preferablynot more than 20 percent, of impurities, depending on the method ofsynthesis and purification scheme(s), if any, employed in theproduction.

In one embodiment, the formulation comprises at least one aryl alkylalcohol of the general formula (II).

where R₁, R₂, R₃, R₄, and R₅ can be hydrogen, deuterium, fluorine,bromine, iodine, chlorine, or alkyl groups. Examples of aryl alkylalcohols include, but are not limited to benzyl alcohol.

In one aspect, the composition of the present invention contains 1 wt %to about 80 wt % of the phosphoric or thiophosphoric triamide. Inanother aspect, the composition of the present invention contains 10 to75 wt. % of the phosphoric or thiophosphoric triamide. In another aspectthe composition of the present invention contains 20 to 50 wt % of thephosphoric or thiophosphoric triamide. In another aspect, thecomposition of the present invention contains 30 to 40% w/w of thephosphoric or thiophosphoric triamide. In one aspect the phosphoric orthiophosphoric triamide is N-(n-butyl) thiophosphoric triamide.

Optionally, the formulation can also contain additional components,including co-solvents. In one embodiment, the additional co-solvent is aglycol or glycol derivative. Examples of glycols can be represented bythe general formula C_(n)H_(2n)(OH)₂, where n is 2 to 12. In someembodiments, n is 3. Glycols also include aliphatic dihydroxy (dihydric)alcohols. Examples of glycols (diols) are ethylene glycol (glycol),propylene glycol (1,2-propanediol), 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, 1,10-decanediol, 1,7-heptanediol, 1,9-nonanediol,1,8-octanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol,2,3-butanediol, 2,4-pentanediol, 2,5-hexanediol, 4,5-octanediol and3,4-hexanediol. Examples of other noncyclic glycols (diols) are neopentyglycol pinacol, 2,2-diethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol,2-ethyl-2-butyl-1,3-propanediol, isobutylene glycol,2,3-dimethyl-1,3-propanediol, 1,3-diphenyl-1,3-propanediol,3-methyl-1,3-butanediol. Examples of cyclic glycols are1,4-cyclohexanedimethanol and p-xylylene glycol. Examples of polyglycolsare polyethylene glycols and polypropylene glycols.

Examples of glycol (diol) derivatives which are esters are ethyleneglycol monostearate ethylene glycol distearate, ethylene glycol amidostearate, propylene glycol monostearate, propylene glycol dicaprylate,propylene glycol dicaprate diacetate glycol, dilaurate glycol, dipalmiteglycol, diformate glycol dibutyrate glycol dibenzorate glycol, dipalmateglycol dipropionate glycol, monostearate glycol monopalmitate glycol andmonoformate glycol. Diethylene glycol monostearate is also an esterderivative.

Examples of polyglycol (polydiol) derivatives which are esters arepolyethylene glycol (PEG) 200-6000 mono and dilaurates, such as, PEG 600dilaurate, PEG 600 monolaurate. PEG 1000 dilaurate, PEG 1000monolauraie, PEG 1540 dilaurate and PEG 1540 monolaurate, polyethyleneglycol 200-6000 mono and dioleates, such as, PEG 400 monoleate, PEG 600dioleate, PEG 600 monooleate, PEG 1000 monoleate, PEG 1540 dioleate, PEG1540 monooleate and polyethylene glycol 200-6000 mono and distearates,such as, PEG 400 distearate, PEG 400 monostearate, PEG 600 distearate,PEG 600 monostearate, PEG 1000 distearate, PEG 1000 monostearate, PEG1540 distearate, PEG 1540 monostearate and PEG 3000 monostearate.

Glycerol (glycerine) is a triol glycerol. Examples of glycerol estersare glycerol monostearate, glycerol distearate, glycerol monooleate,glycerol monolaurate, glycerol dilaurate, glycerol dipalmitate, glycerolmonopalmitate, glycerol triacetate, glycerol tribenzoate, glyceroltributyrate, glycerol trimyristate, glycerol trioleate, glyceroltrilaurate, glycerol tripalmitate and glycerol tristearate.

The content of the additional solvent in compositions which contain thesame is the remainder of mixture with the composition of NBPT and atleast one aryl alkyl alcohol. Thus in one group of embodiments, thecontent of the additional solvent can be between about 99 percent byweight and about 5 percent by weight, or between about 70 percent byweight and about 10 percent by weight together with the combination ofthe N-(alkyl) thiophospboric triamide in the same concentration rangesdescribed for composition with the aryl alkyl alcohol as the solesolvent. In other embodiments, the mixed content of the composition ofthe invention is between about 99 percent by weight and about 50 percentby weight, and preferably between about 70 percent by weight and about80 percent by weight, based upon the only other component of theformulation being the N-(alkyl) thiophosphoric triamide ureaseinhibitor.

The solvents according to the present invention have properties that areadvantageous for their use in agriculture such as: (1) improvedstability of the active ingredient urease inhibitor, such as N-(n-butyl)thiophosphoric triamide (NBPT); (2) excellent solubilitycharacteristics; (3) extremely low flammability of the solvents; (4)reduced toxicity and/or health risk relative to the use of NMP and/orPVP which greatly simplifies the handling and/or storage of thesolution; (5) resistance to solidifying under cold temperatures withoutthe use of additional crystallization inhibitors; and (6) goodadsorption characteristics onto other solid components such as urea forsolid fertilizer compositions and excellent miscibility with liquid ureacontaining fertilizer formulations, which may contain water. Anotheradvantage is their low cost.

Other Optional Components

Other optional components may be used in compositions of the presentinvention. Examples of other agents, include but are not limited to anitrification inhibitor, a conditioner, xanthan gum, calcium carbonate(agricultural lime) in its various forms for adding weight and/orraising the pH of acidic soils; metal containing compounds and mineralssuch as gypsum, metal silicates and chelates of various micronutrientmetals such as iron, zinc and manganese; talc; elemental sulfur;activated carbon, which may act as a “safener” to protect againstpotentially harmful chemicals in the soil; a plant protectant; anutrient stabilizer, super absorbent polymers, wicking agents, wettingagents, plant stimulants to accelerate growth, an inorganic nitrogen,phosphorus, potassium (N-P-K) type fertilizer, sources of phosphorus,sources of potassium, and organic fertilizers, surfactants, such asalkylaryl polyether alcohols; initiators, stabilisers, cross linkers,antioxidants, UV stabilizers, reducing agents, dyes, such as blue dye(ED & C blue #1); and plasticizers. Examples of conditioners include butare not limited to tricalcium phosphate, sodium bicarbonate, sodiumferricyanide, potassium ferricyanide, hone phosphate, sodium silicate,silicon dioxide, calcium silicate, talcum powder, bentonite, calciumaluminum silicate, stearic acid, and polyacrylate powder. Examples ofplant protectants and nutrient stabilizers include silicon dioxide, andthe like.

Nitrification inhibitors are compounds which inhibit the conversion ofammonium to nitrate and reduce nitrogen losses in the soil. Examples ofnitrification inhibitors include, but are not limited to, dicyandiamide(DCD), and the like. The DCD of the present invention can have aparticle size in the range from about 50 to 350 μm.

The content of the additional, components can be from about 1 to about99 percent by weight of the composition. For example, the amount of theadditional components in the composition can be about 1, 2, 3, 4, 5, 6,7, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,98 or about 99% by weight of the total granular fertilizer composition.If DCD is present it may be in the range of about 40 to 95. The ratio ofNBPT to DCD should exceed a value of about 0.02, in some embodiments isbetween about 0.02 and about 10.0, and in some embodiments is betweenabout 0.04 and about 4.0.

The utilization of both 3 urease inhibitor and a nitrificationinhibitor, in the fertilizer composition of this invention offers anopportunity to tailor the make-up: of the composition to match thenitrogen nutrient demand of a given crop/soil/weather scenario. Forexample, if the soil is characterized by a low pH and/or if rain isanticipated shortly after fertilizer application and the opportunity forammonia losses through volatilization to the atmosphere is therebydiminished, the level of the NBPT urease inhibitor incorporated into theformulation may be reduced, within the specified range, without alsochanging the level, of the DCD nitrification inhibitor. The relativeresistance of the fluid fertilizer composition of this invention to ureahydrolysis and ammonia oxidation is controlled by properly selecting theNBPT to DCD weight ratio of the composition. This ratio should exceed avalue of about 0.01, or between about 0.02 and about 8.0, or be betweenabout 0.05 and about 1.0. Fluid fertilizer compositions with NBPT to DCDweight ratios near the higher end of these ranges will exhibitrelatively higher resistance to urea, hydrolysis than to ammoniumoxidation, and vice versa.

Compositions with UFP

Another object of the present Invention is the use of the liquidcomposition containing the phosphoric or thiophosphoric triamidederivative in compositions that can be used, in urea-containingfertilizers. In some applications, a UFP has been used as a carrier forNBPT (see e.g. U.S. Patent Publication 2007/0152689). Accordingly, inanother group of embodiments, the solutions of the present invention aresuitable for deposited the NBPT into the UFP.

The solid UFP of the present invention can be any form of UFP. Examplesof solid UFP include PERGOPAK M® 2, available from Albemarle Corporationand NITAMIN 36S, available from Koch Agronomic Services, LLC. The solidUFP is present in the composition in the range of about 3 to 80%.

The means by which the NBPT and aryl alkyl alcohol composition isdeposited onto the UFP can be selected front any method known. In onegroup of embodiments, the one or more active agents are deposited ontothe UFP by using a drying device such as a high shear mixer, ribbondoer, blade drier, or other similar device. In one group of embodiments,the drying device is a ribbon drier or blade drier.

Typically, one or more active agents are coated onto the UFP byintroducing into the drying device the UFP and a solution comprisingNBPT and aryl alkyl alcohol.

The amount of UFP used may vary and will usually depend on theparticular application, as well as the optional presence of othercomponents besides the UFP used in the present invention. The solutioncomprising NBPT and aryl alkyl alcohol typically contains from about 20to 60 wt. % of the NBPT, based on the weight of the solution, of the oneor more active agent(s). In one group of embodiments, the solutioncomprises from about 25 to 50 wt %, based on the total weight of thecomposition. In one group of embodiments, the solution comprises fromabout 30 to about 35 wt. % of the active agent based, on the totalweight, of the composition. In a further embodiment of the invention,the composition contains from about 1 to 55% UFP and from about 99.0 to70.0% BCD. Without DCD, the composition may contain about 1 to 80% NBPTand about 99 to 20% UFP.

In the practice of this embodiment of the present invention, the UFP andthe NBPT and aryl alkyl alcohol solution can be introduced into thedrying device simultaneously, in stages, either the UFP or the NBPT andaryl alkyl alcohol solution can be introduced before the other, or anycombinations thereof. Thus, this embodiment of the present invention canbe either a batch or continuous process. In one group of embodiments,the NBPT and aryl alkyl alcohol solution is introduced into the dryingdevice alter the UFP. In this and other embodiments, the introduction ofthe active agent solution is controlled to avoid over-wetting of theUFP. Over-wetting can be prevented by introducing the active agentsolution into the drying device at a rate substantially equal to therate at which the solvent volatilizes. The volatilization, of thesolvent is achieved by operating the drying device under conditions thatinclude a temperature that is below the melting point of the activeagent(s) and below the boiling point of the solvent. In one group ofembodiments, the drying device is operated under such a temperature anda sub-atmospheric pressure. In one group of embodiments, thetemperatures under which, the drying device is operated are in the rangeof from about 20° C. to about 200° C., or in the range of from about 20°C. to about 100° C., or from about 20° C. to about 50° C. Also, asstated above, the drying device may be operated under sub-atmosphericpressures, i.e. under a vacuum. These pressures may be in the range offrom about 760 mmHg to about 0.1 mmHg, or in the range of from about 500mmHg to about 50 mmHg, or from about 100 mmHg to about 50 mmHg.

Fertiliser Compositions

The resulting solid is then blended directly with granulated urea or beused as an additive to liquid urea.

Solid Urea-Based Fertiliser Compositions

Urea Fertilizer Base

The urea-based granular fertilizer of the present invention can includeany suitable quantity of a urea source and contains one or moreadditional components. In one group of embodiments, the urea source isgranulated solid or prilled urea. One of skill in the art willappreciate other urea sources for the inventive methods. The amount ofthe urea source in the urea-based granular fertilizer can range frontabout 1% to about 99% by weight of the total granular fertilizercomposition. The amount of the urea source in the urea-based granularfertilizer can be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68,69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 or about 99% or more byweight of the total granular fertilizer composition.

In another group of embodiments, the present invention provides aurea-based granular fertilizer composition comprising:

a) a urea source of from about 95% to 99.075% by weight of the totalgranular fertiliser composition;

b) a composition of NBPT and aryl alkyl alcohol as described above inthe range of from about 0.025% to 5% by weight of the total granularfertilizer composition.

Thus in one embodiment, the urea content of the composition, of thisinvention is between about 90% and about 99% by weight, andalternatively between about 92% and about 99% by weight. The content ofthe NBPT composition is between about 0.02% and about 0.5% by weight, orbetween about 0.04% and about 0.4% by weight DCD may account for about0.01% to about 1.2% by weight of the composition, and in someembodiment's accounts for between about 0.05% and about 1.1% by weightof the composition. The composition may also contain some moisture, ureasynthesis byproducts, and an aryl alkyl alcohol, and as noted above mayoptionally contain other additives, such as a dye, an NBPT stabilizer,or a micronutrient. The diameter of the granules of the improvedhomogenous urea-based fertilizer composition of this invention rangesfrom about 0.5 millimeters to about 10 millimeters, and in someembodiments from about 0.8 millimeters to about 0.9, to about 1.0, toabout 1.1, to about 1.2, to about 1.3, to about 1.4, to about 1.5, toabout 1.6, to about 1.7, to about 1.8, to about 1.9, to about 2.0, toabout 2.1, to about 2.2, to about 2.3, to about 2.4, to about 2.5, toabout 2.6, to about 2.7, to about 2.8, to about 2.9, to about 3.0, toabout 3.1, to about 3.2, to about 3.3, to about 3.4, to about 3.5, toabout 3.6, to about 3.7, to about 3.8, to about 3.9, to about 4.0, toabout 4.1, to about 4.2, to about 4.3, to about 4.4, to about 4.5, toabout 4.6, to about 4.7, and to about 4.8 millimeters.

Processes for Making Solid Urea-Based Fertilizer Composition

In one aspect, the present invention provides a method, wherein the NBPTcomposition is blended or mixed with the urea. The conditioner whenmixed or blended with a urea-based fertilizer provides a urea-basedfertilizer that has improved storage and handling properties.

In one group of embodiments, the present invention provides acomposition similar to wherein commercial fertilizers, including, butnot limited to SUPER U®; UFLEXX®; UMAXX®; or granular urea treated withAGRGTAIN DRY®.

In one group of embodiments, the NBPT and UFP composition, canincorporated into the homogenous urea-based fertilizer composition byblending, either dry or as a concentrated solution of NBPT and UFP in anaryl alkyl alcohol solvent on urea. The incorporation can be done atambient conditions or on molten urea at a temperature of about 266° F.to about 275° F. prior to the granulation or prilling of the urea in aconventional urea production facility. Sufficient mixing is employedduring this blending step to assure that the NBPT, UFP and aryl alkylalcohol solution is homogeneously distributed, especially before themelt cools and solidifies in the subsequent granulation step if moltenurea is used.

The NBPT, UFP and aryl alkyl alcohol solution of this invention remainsstable over extended periods of time and over temperatures ranging fromabout 30° F. to about 120° F. Thus, both the solid and liquid forms ofthe NBPT and UFP composition of this invention can be managed usingconventional storage, transportation, and pumping equipment,

The amount of NBPT and UFP compositions of the present invention addedto urea in accordance with this invention in either solid or liquid formdepends on the desired NBPT content of the granular fertilizercomposition and can be readily calculated by those skilled in the art.In some embodiments, no or only very limited quantities of aryl alkylalcohol are introduced into the urea along with the NBPT and UFP. Forexample, if the NBPT and UFP content of the NBPT, UFP and aryl alkylalcohol solution used to incorporate the NBPT and UFP in the fertilizercomposition is 70% and the NBPT content of the resulting fertilizercomposition is 0.07%.

In some embodiments, DCD can also be added to and blended with the ureaat this point in the formulation rather than during the formulation withthe UFP. Several methods can be used for the introduction of DCD intosolid or molten urea: if available as a powder or in granular form, theDCD can be fed into a stream of solid or molten area using aconventional solids feeding device; or, the DCD may be dissolved in arelatively small quantity of molten urea, as for example in a sidestream of molten urea in a urea plant, to form a concentrated DCDsolution in molten urea which is then metered into the main stream, ofthe solid or molten urea. Finally, the DCD may be incorporated into theNBPT, UFP and aryl alkyl alcohol solution described hereinabove andintroduced into the urea or molten urea along with the NBPT, UFP andaryl alkyl alcohol solution. Regardless of the method selected tointroduce the DCD into the urea, sufficient mixing should be provided tofacilitate homogenous distribution of the DCD throughout the urea. Thehomogeneous distribution of the NBPT, the UFP and DCD in the granularfertilizer compositions of this invention enhances the performance ofthese compositions in terms of their ability to promote plant growth.

The order in which the NBPT and UFP composition and the DCD are added tothe urea in the practice of this invention is flexible: either the NBPTand UFP composition or DCD may be introduced first, or both of thesecomponents may be added simultaneously. In one group of embodiments, theDCD is added first to provide adequate time for both the dissolution anduniform distribution of the DCD in the molten urea prior to thegranulation step. A convenient point for the addition of DCD to urea. Ina urea production plant is before or between any evaporation steps usedto reduce the water content of the urea. The NBPT and UFP composition,however, may be introduced into the molten urea, just prior to thegranulation or prilling step with only sufficient, retention time in themelt to allow for uniform distribution of the NBPT in the melt. In onegroup of embodiments, the retention time of the melt between the pointof the NBPT and UFP composition addition and the granulation step isless than 5 minutes, or less than 1 minute.

After the NBPT and UPP composition is combined with the urea, thegranules may be sized. In one group of embodiments, granules which passthrough a 4 mesh Tyler Series sieve (about 4.76 millimeters) and stay ona 20 mesh Tyler Series sieve (about 0.84 millimeters) are retained asproduct. The undersized particles may be recycled and the oversizedparticles may be ground and/or recycled.

Liquid Urea-Based Composition

The present invention also provides an improved fluid urea-ammoniumnitrate (UAN) fertilizer composition containing the NBPT composition.Specifically, the improved fluid fertilizer composition of thisinvention Is comprised primarily of an aqueous solution of urea,ammonium nitrate, and the NBPT composition, and optionally dicyandiamide(DCD),

The urea content of the composition of this invention is between about24% and about 32% by weight or between about 26% and about 32% byweight; the ammonium nitrate content of the composition is between about34% and about 42% by weight, or between about 36% and about 42% byweight; the NBPT content of the composition is between about 0.01% andabout 0.4% by weight, or between about 0.02% and about 0.3% by weight;and the DCD accounts for about 0% to about 2.0% by weight of thecomposition, and may account for between about 0.03% and about 1.5% byweight of the composition. The balance of the composition consistsprimarily of water. An aryl alkyl alcohol solvent for the NBPT asdisclosed above, may also be present in small quantities.

Processes for Making Liquid Urea-Based Compositions

In accordance with the present invention, the NBPT composition may beincorporated into the fluid fertilizer composition by adding a solid orliquid form of the NBPT composition directly to a UAN fluid withsufficient mixing to assure that the NBPT is homogeneously distributedthroughout the fluid fertilizer composition. Both the solid and liquidforms of the NBPT composition as disclosed above can be introduced intoUAN using conventional metering devices.

The amount of the NBPT composition in accordance with this inventiondepends on the desired NBPT content of the fertiliser composition withinthe ranges specified hereinabove and on the NBPT, and aryl alkyl alcoholsolution, and can be readily calculated by those skilled in the art.

Like the solid formulation, DCD can also be added to the UAN fluid atthis stage, rather than with the UFP, alone. Several methods areavailable for the introduction of DCD into UAN. If available as a powderor in granular form, the DCD can be fed into UAN fluid using aconventional solids feeding device. In one group of embodiments,however, the DCD is first incorporated into a relatively small quantityof UAN fluid so as to form a slurry of DCD in UAN fluid; this slurry isthen blended with the balance of the UAN fluid in the amount needed toprovide the desired concentration of DCD within the ranges specifiedhereinabove. Regardless of the method selected to introduce the DCD intothe UAN fluid, sufficient mixing should be provided to facilitatehomogenous distribution of the DCD throughout the UAN fluid. Thehomogeneous distribution of both the NBPT composition and DCD In thefluid fertilizer compositions of this Invention enhances the performanceof these compositions in terms of their ability to promote plant growth.

The order in which the NBPT composition and DCD are added to the fluidfertilizer in the practice of this invention, is flexible: either theNBPT composition or DCD may be introduced first, or both of thesecomponents may be added simultaneously. However, in light of therelative instability of NBPT in aqueous solutions, solid or liquid formsof the NBPT composition may be introduced into the fluid fertilizerrelatively late in production-storage-distribution sequence of the fluidfertiliser, so as to minimize the time span between the addition of theNBPT composition to the fluid fertilizer and the application of thefertilizer to the soil.

The NBPT composition is added to the UAN solution in the range of about0.01 to 5.0% additive in the final product. In one group of embodiments,the NBPT composition is added in the range of about 0.4 to 2.5% to fluidUAN or urea solution, or blends thereof, to form a fluid fertilizer. Thefluid urea-based fertilizer of the present invention contains from about0.004 to 1.50% NBPT, from about 0 to 0.850% DCD, and from about 99.9 to97.0% aqueous UAN. Optionally, the fertilizer can contain up to about0.03% silicon, dioxide. The aqueous UAN contains urea and ammoniumnitrate in concentration ranges of about 15 to 50%. In one group ofembodiments, the range is from about 25 to 40%.

Use

The granular fertilizer composition of this invention made by themethods described herein can be used in ail agricultural applications inwhich granular fertilizer compositions are currently used. Theseapplications include a very wide range of crop and turf species, tillagesystems, and fertilizer placement methods. The fertilizer grannies madewith the NBPT composition of present invention are useful forfertilizing a wide variety of seeds and plants, including seeds used togrow crops for human consumption, for silage, or for other agriculturaluses. Indeed, virtually any seed or plant can be treated in accordancewith the present invention using the compositions of the presentinvention, such as cereals, vegetables, ornamentals, conifers, coffee,turf grasses, forages and fruits, including citrus. Plants that can betreated include grains such as barley, oats and corn, sunflower, sugarbeets, rape, safflower, flax, canary grass, tomatoes, cotton seed,peanuts, soybean, wheat, rice, alfalfa, sorghum, beau, sugar cane,broccoli, cabbage and carrot.

The granular urea-based fertilizer composition of this invention can beused in all agricultural applications in which granular urea iscurrently used. These applications include a very wide range of crop andturf species, tillage systems, and fertilizer placement methods. The newimproved composition increases the nitrogen uptake by plants, enhancescrop yields, and minimizes the loss of both ammonium nitrogen andnitrate nitrogen from the soil.

The rate at which the fertilizer composition of this invention isapplied to the soil may be identical to the rate at which urea iscurrently used for a given application in the case of the composition ofthis invention. Alternately, the composition of this invention may beapplied to the soil at lower rates than is the case for urea. It is ofinterest to illustrate the quantities of NBPT and DCD introduced intothe soil when a given, composition of this invention is applied as afertilizer. For example, assuming that the composition is applied, tothe soil at a rate of 100 pounds per acre and that it contains 0.1% NBPTand 1% DCD, it can be readily calculated that the rates of NBPT and DCDapplication are 0.1 and 1.0 pounds per acre, respectively.

The UAN-based fertilizer composition of this invention can be used inall agricultural applications in which UAN Is currently used. Theseapplications include a very wide range of crop and turf species, tillagesystems, and fertilizer placement methods. The fertilizer composition ofthis invention can be applied to a field crop, such as corn or wheat, ina single surface application, and will nevertheless supply sufficientnitrogen to the plants throughout their growth, and maturing cycles.

The rate at which the fertilizer composition of this invention isapplied to the soil may be identical to the rate at which UAN iscurrently used for a given application. Alternately, the composition ofthis invention may be applied to the soil at lower rates than is thecase for DAM and still provide comparable crop yields, but with a muchlower potential for nitrogen loss to the environment. It is of interestto illustrate the quantities of NBPT and DCD introduced into the soilwhen a given composition of this invention is applied as a fertilizer.For example, assuming that the composition is applied to the soil at arate of 200 pounds per acre and that it contains 0.05%. NBPT and 0.5%DCD, it can be readily calculated that the rates of NBPT and DCDapplication are 0.1 and 1.0 pounds per acre, respectively,

The following examples are intended to illustrate, but not to limit, themethods and compositions of the invention. All percentages describedherein are by weight, unless otherwise indicated,

EXAMPLES

The following describes examples of compositions of NBPT of the presentinvention. The compositions are prepared by dissolving at least 25 wt. %of NBPT in the following solvents with stirring to form, clearsolutions. The dissolution of example 3 proceeded easily,

Example 1

A concentrated solution of N-(n-butyl) thiophosphoric triamide (NBPT)was prepared according to the following: Molten commercial NBPT (63.6 g,˜84% NBPT) was added to benzyl alcohol (118.11 g) and the resultingliquid was shaken for 30 seconds and allowed to cool to rt. The NBPTconcentration of this solution was approximately 29%.

Example 2

To the NBPT solution from Example 1 was added propylene glycol (17.84 g)to give a final NBPT concentration of 26.7% and a green dye (0.448 g)and the mixture was stirred at rt until complete dissolution of the dye(˜10 min).

Example 3

Molten commercial NBPT (16 g, ˜84% NBPT) was added to warmed (40° C.)benzyl alcohol (34 g) and the resulting liquid was shaken for 30 secondsand allowed, to cool to rt. The NBPT concentration of this solution wasapproximately 26.7%.

Example 4

A concentrated solution of N-(n-butyl) thiophosphoric triamide (NBPT)was prepared according to the following: Molten commercial NBPT (54.5g, >97% NBPT) was added to benzyl alcohol (130.8 g) and the resultingliquid was shaken for 30 seconds and allowed to cool to rt. The NBPTconcentration of this solution was approximately 29%.

Example 5

Molten commercial NBPT (13.4 g, ˜97% NBPT) was added to warmed (40° C.)benzyl alcohol (36.6 g) and the resulting liquid was shaken for 30seconds and allowed, to cool to rt. The NBPT concentration of thissolution was approximately 26.7%,

Urea Coating

Example 6

To 100 g urea was added 0.34 g of the NBPT solution from Example 2 in asealable cup. The lid was securely fastened and the mixture was shakenfor 1 min. The resulting urea was uniformly coated with the NBPT asindicated by the uniformity of the green dye covering the urea.

Example 7

100 g of urea was added 0.34 g of the NBPT solution from Example 4 in asealable cup. The lid was securely fastened and the mixture was shakenfor 1 min. The resulting urea was uniformly coated with the NBPT asindicated by the uniformity of the green dye covering the urea.

Example 8

The stability and the capability of the solutions of N-(n-butyl)thiophosphoric triamide (NBPT) in the solvent systems of the presentinvention to remain liquid at low temperatures (flowability) isassessed. A 26.7 wt. % solution of NBPT in the binary solution ofExample 2 is stored ford months at 0° C. and the presence of crystals inthe solutions and the flowability of the solutions is assessed.

For comparison with the prior art, a mixture containing propylene glycol(PG) with 10 wt. % N-methylpyrrolidone (NMP) described in the U.S. Pat.No. 5,698,003 and a mixture containing 90 wt. % dipropylene glycolmonomethyl ether with 10 wt. % N-methylpyrrolidone (NMP) described in WO2008/000196 was used. The following observations were made. The mixtureof U.S. Pat. No, 5,698,003 crystallized under said conditions. While themixture of the present invention and of WO 2008/000196 did notcrystallize under said conditions, the binary solution of die presentcontained no polyvinylpyrrolidone or NMP, surprisingly showing that theaddition of crystallization inhibitors is not necessary. Other binaryand ternary solvent systems of the present invention have similarproperties. All solvent systems of the present invention arewater-miscible.

Example 9

A highly stable solution of N-(n-butyl) thiophosphoric triamide (NBPT)is a key feature for its use and long-term storage of its solutions. Thepresence of water causes the decomposition of NBPT into non-effectivesubstances during a longer storage and is the main cause of the NBPTdegradation during a long-term storage.

The solvent systems of the present invention show a stabilizing effecttowards NBPT. All solvents used in this example are commerciallyavailable in a very good quality, having the water content lower than0.1 wt. %. Nevertheless, to confirm the stabilization effect of thesolvents, the wafer content was artificially increased to 1 wt %. Thethus adjusted solvent systems simulate the effect of the moisture onNBPT (higher contents of the moisture than 1 wt. % are uncommon).

In order to verify the long-term stability of NBPT, the followingsolvents containing less than 0.1 wt. % of water were tested. 20 wt. %solutions of NBPT were stored at room temperature at daylight in glass,well-sealed vials. The monitoring of any degradation NBPT was carriedout by reverse-phase HPLC with UV detection in the mobile phasecontaining 25 vol. % acetonitrile and 75 vol. % 0.005M ammonium acetate.The chromatogram was evaluated at the wavelength of 193 nm. The mobilephase flow was 1 ml/min, the column temperature was 40° C. The injectedvolume was 5 μl. The evaluation was carried out by the method ofexternal standard with the calibration using a calibration, line. USD Isthe relative deviation in rel. %, calculated from three repeats ofsampling and two repeats of analysis of each, sample.

The solvent systems of the present invention have a stabilizing effecttowards NBPT. After 12 weeks of storage, no significant decrease of thecontent of the active component NBPT occurred in any sample (the methodused can determine the change of approx. at least 1 wt. %).

Example 10 Granular Urea Formulation with Formulation of Example 6

As a first step, a 121,000 lb. batch of NBPT solution of Example 1 waspumped at a rate equivalent to 4 pounds of NBPT per 1996 pounds of ureainto a 34 ton/hour stream of molten urea passing through a pipe, leadingfrom the last stage of urea evaporation directly to the urea granulationapparatus in a urea production facility. The temperature of the moltenurea at the point at which, the NBPT solution was injected was about275° F. Although the retention time of the urea stream between the pointat which the concentrated NBPT solution was injected and the ureagranulation, apparatus was only in the order of 20 seconds, the degreeof turbulence in the stream of molten urea assured thorough mixing andhomogenous distribution of the concentrated NBPT solution in the moltenurea. The urea production facility was operated in this mode for aperiod of about 8.5 days, during which time about 6960 tons of ureacontaining 0.2% NBPT was produced. The fertilizer was tested for theuniformity of distribution of NBPT. The NBPT was uniformly distributedthrough each granule of the product.

Example 11 Liquid Urea Formulation with Liquid Formulation of NBPT

This example illustrates the method of this invention for theincorporation of the NBPT composition into a fluid urea-containingfertilizer composition. The formulation of Example 1 was added at a rateequivalent to 2 pounds of NBPT per 1998 pounds of DAN solution into a 50ton/hour stream of DAN solution containing 30% urea and 40% ammonium,nitrate and approximately 10 pounds per ton DCD. Said stream of DANsolution was being transferred from a liquid storage tank into liquidrail cars. Although the retention dine of the DAN solution between thepoint near the liquid storage tank at which the concentrated NBPTsolution was injected into the DAN solution and the point at which thesolution was discharged into the rail car was only in the order of 40seconds, the degree of turbulence in the stream of DAN solution assuredthorough mixing and homogenous distribution of the concentrated NBPTsolution in the UAN solution. A set of rail cars was filled in thismanner with a total of about 1400 tons of UAN solution containing about0.1% NBPT.

Example 12 Granular Urea Formation with Example 1

This example illustrates the method of this invention for theincorporation of the NBPT composition into a granular urea-containingfertilizer composition. The test was conducted in an industrial facilitywith a urea production rate of 34 tons per hour. DCD was introduced intothe molten urea at a rate of 20 pounds of DCD per 1976 pounds of ureabefore the last stage of evaporation that is at a point in thecontinuous urea scheme where the molten urea has a moisture content ofabout 4-6%. Thorough mixing was provided to assure homogeneousdistribution of the DCD in the urea melt. The DCD-containing molten ureathen passes through the last evaporator to reduce its moisture contentto about 1%. A concentrated NBPT solution of Example 1 was pumped Intothe DCD-containing molten urea stream at a rate equivalent to 4 poundsNBPT per 1996 pounds of DCD-containing molten urea. The temperature ofthe molten urea at the point at which the NBPT solution was injected wasabout 275° F. The resulting stream of NBPT- and DCD-containing moltenurea was next directed through a pipe leading directly to thegranulation apparatus in a urea production facility. Although theretention time of the NBPT- and DCD-containing molten urea streambetween the point at which the concentrated NBPT solution was injectedand the urea granulation apparatus was only in the order of 20 seconds,the degree of turbulence in the stream of molten urea compositionassured thorough mixing and homogenous distribution of the concentratedNBPT solution in the DCD-containing molten urea.

The solutions of N-(alkyl) phosphoric or thiophosphoric triamides in thesolvent systems of the present, invention can be long-term stored, usedfor the Impregnation of solid urea-containing fertilizers, such asgranular urea, added into the mixture for the manufacture of solidurea-containing fertilizers or added into liquid urea-containingfertilizers. They can also be used as a suitable urease inhibitorformulation, for addition into animal wastes or sprays masking urineodor.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, one of skill in the art will appreciate that certainchanges and modifications may be practiced within the scope of theappended claims. In addition, each, reference provided herein isincorporated by reference in its entirety to the same extent as if eachreference was individually incorporated by reference. Where a conflictexists between the instant application and a reference provided herein,the instant application shall dominate.

What is claimed is:
 1. A composition comprising: (i) a urease inhibitor;(ii) a dye; and (iii) a solvent comprising a glycol or glycol derivativeand at least one aryl alkyl alcohol of formula (II),

wherein R₁, R₂, R₃, R₄, and R₅ are independently hydrogen, deuterium,fluorine, bromine, iodine, chlorine, or alkyl.
 2. The composition ofclaim 1, wherein the at least one aryl alkyl alcohol is benzyl alcohol.3. The composition of claim 1, wherein the glycol or glycol derivativeis propylene glycol.
 4. The composition of claim 1, wherein the ureaseinhibitor is a phosphoric or thiophosphoric triamide of formula (I),X═P(NH₂)₂NR¹R²  (I) wherein X is oxygen or sulfur, and R¹ and R² areindependently hydrogen, C₁-C₁₂ alkyl, C₃-C₁₂ cycloalkyl, C₆-C₁₄ aryl,C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₄ heteroaryl, C₁-C₁₄ heteroalkyl,C₂-C₁₄ heteroalkenyl, C₂-C₁₄ heteroalkynyl, or C₃-C₁₂ cycloheteroalkyl.5. The composition of claim 1, wherein the urease inhibitor isN-(n-butyl) thiophosphoric triamide (NBPT).
 6. The composition of claim5 comprising about 1 to 99 wt. % of N-(n-butyl) thiophosphoric triamide(NBPT).
 7. The composition of any one claim 1, wherein the solventcomprises about 1 wt. % to about 99 wt. % benzyl alcohol based on thetotal weight of solvent.
 8. The composition of claim 1, wherein thesolvent comprises about 1 wt. % to 70 wt. % propylene glycol based onthe total weight of solvent.
 9. The composition of claim 1 furthercomprising one or more components selected from the group consisting ofa conditioner and xanthan gum.
 10. A composition comprising a) a ureaformaldehyde polymer and b) the composition of claim
 1. 11. Acomposition comprising a) urea and b) the composition of claim
 1. 12. Acomposition comprising a) urea, b) a nitrification inhibitor, and c) thecomposition of claim
 1. 13. The composition of claim 12, wherein theurease inhibitor is a phosphoric triamide or thiophosphoric triamide offormula (I),X═P(NH₂)₂NR¹R²  (I) wherein X is oxygen or sulfur, and R¹ and R² areindependently hydrogen, C₁-C₁₂ alkyl, C₃-C₁₂ cycloalkyl, C₆-C₁₄ aryl,C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₅-C₁₄ heteroaryl, C₁-C₁₄ heteroalkyl,C₂-C₁₄ heteroalkenyl, C₂-C₁₄ heteroalkynyl, or C₃-C₁₂ cycloheteroalkyl.14. The composition of claim 13, wherein the urease inhibitor isN-(n-butyl) thiophosphoric triamide (NBPT).
 15. The composition of claim14, wherein the nitrification inhibitor is dicyandiamide (DCD).
 16. Amethod of manufacturing a fertilizer, the method comprising: using thecomposition of claim 1 in the manufacture of the fertilizer.
 17. Thecomposition of claim 1 made by contacting the urease inhibitor with thearyl alkyl alcohol, separately contacting the dye with the glycol orglycol derivative, and combining the resulting mixtures.
 18. Thecomposition of claim 10 made by contacting the urea-formaldehyde polymerwith the composition of claim
 1. 19. The composition of claim 11 made bycontacting urea with the composition of claim
 1. 20. The composition ofclaim 1, wherein the composition comprises about 5 wt. % to 99 wt. % ofthe glycol or glycol derivative based on the total weight of thecomposition.
 21. The composition of claim 1, wherein the dye is a greenor blue dye.